DENOX abatement plants through special catalytic beds and urea injection.
Airprotech is supplying DeNOx plants for many years
in different industrial sectors.
This kind of application is recently requested in co-generation
field, in particular downstream of internal combustion
motors powered by biodiesel or by vegetable oils. Such
combustibles give high advantages compared to diesel
but, at the same time, produce bigger quantity of NOx
and accordingly require an appropriate abatement system
in order to respect the emission limits required by
The most effective process to eliminate nitrogen oxides
(NOx) is the one based on the selective catalytic reduction
(SCR), technology that takes advantage of the tendency
of ammonia (contained in urea) to react with nitrogen
oxides in presence of selective catalyst that allows
a high performance.
One of the reactions is:
The polluted air to be treated, coming from the motors,
is sucked up from a centrifugal fan located downstream
of the plant, passes first the blending unit where the
urea is dosed through an air atomization nozzle and
then introduced on the catalysis bed where it meets
with the catalyst on which the reduction reaction occurs
and turns the nitrogen oxides into N2.
Once happened the reaction, the cleaned air that comes
out from the catalysis unit is sent to the atmosphere
through a suitable chimney.
The catalyst chosen for the reduction is honeycomb type
that has titanium as active catalytic component. This
kind of catalyst is poisoning proof and can bear high
If the temperature of the fumes to be treated is particularly
high, it is foreseen the possibility to reduce it by
blending it with ambient air through a modulating valve.
This loop will work in control of the temperature and
in a completely automatic way.